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Sarah Loebner, Nino Lomadze, Alexey Kopyshev, Markus Koch, Olga Guskova, Marina Grenzer Saphiannikova, Svetlana A Santer
We report on light induced deformation of colloidal spheres consisting of azobenzene containing polymers. The colloids of the size between 60nm and 2m in diameter were drop casted on a glass surface and irradiated with linearly polarized light. It was found that colloidal particles can be deformed up to ca. 6 times of their initial diameter. The maximum degree of deformation depends on the irradiation wavelength and intensity, as well as on colloidal particles size. Based on recently proposed theory [V. Toshchevikov et al...
January 16, 2018: Journal of Physical Chemistry. B
Dongyuan Zhao, Tiancong Zhao, Peiyuan Wang, Qin Li, Areej Abdulkareem Al-Khalaf, Wael N Hozzein, Fan Zhang, Xiaomin Li
Nanoparticle based diagnosis-therapy integrative systems represent an emerging approach to cancer treatment. However, a series of size-dependent biological barriers impede nanomedicine from clinical implementation, especially the contradiction on optimum sizes for long blood circulation and quick metabolization. Herein, we demonstrate a novel NIR induced decomposable nanocapsule. The nanocapsules are fabricated based on layer-by-layer assembly of azobenzene functionalized polymers and up/downconversion nanoparticles (U/DCNPs)...
January 16, 2018: Angewandte Chemie
Daniel J Tindall, Christophe Werlé, Richard Goddard, Petra Philipps, Christophe Farès, Alois Fürstner
Traditional rhodium carbene chemistry relies on the controlled decomposition of diazo derivatives with [Rh2(OAc)4] or related dinuclear Rh(+2) complexes, whereas the use of other rhodium sources is much less developed. It is now shown that half-sandwich carbene species derived from [Cp*MX2]2 (M = Rh, Ir; X = Cl, Br, I, Cp* = pentamethylcyclopentadienyl) also exhibit favorable application profiles. Interestingly, the anionic ligand X proved to be a critical determinant of reactivity in the case of cyclopropanation, epoxide formation and the previously unknown catalytic metathesis of azobenzene derivatives, whereas the nature of X does not play any significant role in -OH insertion reactions...
January 14, 2018: Journal of the American Chemical Society
Andrzej Miniewicz, Hanna Orlikowska, Anna Sobolewska, Stanislaw Bartkiewicz
Single-component azobenzene-based phototropic liquid crystals (PtLC) are promising materials that have started to be explored for photonic applications. One of the essential factors determining the applicability of these materials is the rate of the thermally driven cis-trans isomerization. In this paper, the kinetics of the thermal back cis-to-trans reaction in a pure 4-hexyl-4'-methoxyazobenzene (6-AB-O1) compound in its isotropic liquid and nematic phases is studied (the undoped LC). The reaction rate constants, activation energies and thermal activation parameters were determined based on spectroscopic studies...
January 12, 2018: Physical Chemistry Chemical Physics: PCCP
Tomoki Ogoshi, Shu Takashima, Tada-Aki Yamagishi
Using the pillar-shaped architecture of pillar[5]arenes, we constructed microporous multi-layer films with azobenzene groups on the top surface by layer-by-layer assembly of cationic and anionic pillar[5]arenes. Guest uptake, storage and release by the microporous films were regulated through photo-reversible isomerization of azobenzene groups attached to the pore outlets. Azobenzene was regarded as a "molecular valve" to control guest access: the trans form of the azobenzene acted as an open valve, allowing the guest free access from/to the micropores...
January 10, 2018: Journal of the American Chemical Society
Simon Jaekel, Antje Richter, Robert Lindner, Ralf Bechstein, Christophe Nacci, Stefan Hecht, Angelika Kuhnle, Leonhard Grill
Prototypical molecular switches such as azobenzenes exhibit two states, i.e. trans and cis, with different characteristic physical properties. In recent years various derivatives were investigated on metallic surfaces. However, bulk insulators as supporting substrate reveal important advantages since they allow electronic decoupling from the environment, which is key to control the switching properties. Here, we report on the light-induced isomerization of an azobenzene derivative on a bulk insulator surface, in this case calcite (101 ̅4), studied by atomic force microscopy with submolecular resolution...
January 9, 2018: ACS Nano
Kai Müller, Julian Helfferich, Fangli Zhao, Rupal Verma, Anemar Bruno Kanj, Velimir Meded, David Bléger, Wolfgang Wenzel, Lars Heinke
Proton conducting nanoporous materials attract substantial attention with respect to applications in fuel cells, supercapacitors, chemical sensors, and information processing devices inspired by biological systems. Here, a crystalline, nanoporous material which offers dynamic remote-control over the proton conduction is presented. This is realized by using surface-mounted metal-organic frameworks (SURMOFs) with azobenzene side groups that can undergo light-induced reversible isomerization between the stable trans and cis states...
January 8, 2018: Advanced Materials
Jian Li, Shuyan Song, Yan Long, Lanlan Wu, Xiao Wang, Yan Xing, Rongchao Jin, Xiaogang Liu, Hongjie Zhang
Due to the obvious distinctions in structure, core-shell nanostructures (CSNs) and yolk-shell nanostructures (YSNs) exhibit different catalytic behavior for specific organic reactions. In this work, two unique autoredox routes are developed to the fabrication of CeO2 -encapsulated Au nanocatalysts. Route A is the synthesis of well-defined CSNs by a one-step redox reaction. The process involves an interesting phenomenon in which Ce3+ can act as a weak acid to inhibit the hydrolysis of Ce4+ under the condition of OH- shortage...
January 8, 2018: Advanced Materials
Zhiqiang Li, Guannan Wang, Yige Wang, Huanrong Li
We report here on remote-control over reversible phase transition of robust luminescent hybrid hydrogels by rational selection and incorporation of photoswitches into hydrogel systems. Azobenzene units functionalized with guanidinium was utilized as the photoswitches and incorporated via a host-guest inclusion method involving α-cyclodextrins functionalized with 2, 6-pyridinedicarboxylic acid (PDA) groups. While the guanidinium functional groups bind to the negative charged Laponite matrixs surface to connect organic and inorganic components, the PDA groups enable simultaneous coordination with different lanthanide metal ions, rendering the hydrogel broadly luminescent...
January 3, 2018: Angewandte Chemie
Xiao Li, Bo Li, Ming He, Wei Wang, Tianjie Wang, Aurelia Wang, Jiwoo Yu, Zhong Lin Wang, Suck Won Hong, Myunghwan Byun, Shaoliang Lin, Haifeng Yu, Zhiqun Lin
Hierarchically arranged stripes of photoswitchable liquid crystal polymers (LCPs) containing azobenzene moieties were conveniently crafted via flow-enabled self-assembly (FESA). Interestingly, by subjecting a drop of LCP solution to dry in a restricted geometry comprising two nearly parallel plates with a stationary upper plate and a movable lower plate that programmably traveled in a "stop-and-move" manner during the FESA process, photoswitchable LCP stripes were yielded, displaying two modes of deposition, namely, periodic primary stripes of large dimensions and regularly spaced secondary stripes of small dimensions situated between adjacent primary stripes (i...
January 8, 2018: ACS Applied Materials & Interfaces
Jianzhong Jiang, Qianqian Xu, Guozheng Wang, Zhenggang Cui
Stimulus-responsive surfactant wormlike micelles have been widely investigated in the past decade. In this article, we report light and CO2/N2 dual stimuli-responsive wormlike micelles using a zwitterionic surfactant (SDAP) and an azobenzene surfactant (C4AzoC6N). In contrast to traditional amine-containing wormlike micelles, a fast and reversible CO2-triggered thinning behavior was observed. The system can also be reversibly switched by UV irradiation. The dual stimuli-responsive wormlike micelles (C4AzoC6N-SDAP) may have applications in the development of functional materials for microfluidics and analytical chemistry...
January 5, 2018: Soft Matter
Tatsuya Takeshita, Michihiro Hara
Azobenzene (1) and the complex resulting from the incorporation of 1 with cyclodextrin (1/CD) are attractive for light-driven applications such as micromachining and chemical biology tools. The highly sensitive photoresponse of 1 is crucial for light-driven applications containing both 1 and 1/CD to reach their full potential. In this study, we investigated the photoionization and trans-to-cis isomerization of 1/CD induced by one- and two-color two-laser pulse excitation. Photoionization of 1/CD, which was induced by stepwise two-photon absorption, was observed using laser pulse excitation at 266nm...
December 21, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Hongchao Ma, Shuo Li, Yanhui Wei, Lei Jiang, Junbai Li
An azobenzene with a terminal formyl group, named as (4-[(3-Formyl-4-hydroxy)phenylazo]benzene (FHPAB)), was synthesized and used to manipulate the self-assembly of diphenylalanine (FF) molecules. Two-dimensional (2D) thin slices which are composed of ordered microspheres have been constructed through supramolecular self-assembly of FF and FHPAB. The FTIR and XPS results indicate that CN covalent bond between FF and FHPAB was generated. Hydrogen bonding and strong π-π interaction between the planar FF-HFPAB conjugates are the driving force to form the FF-HFPAB 2D thin slices...
December 22, 2017: Journal of Colloid and Interface Science
Guojun Chen, Ben Ma, Ruosen Xie, Yuyuan Wang, Kefeng Dou, Shaoqin Gong
Spatiotemporal control over the release or activation of biomacromolecules such as siRNA remains a significant challenge. Light-controlled release has gained popularity in recent years; however, a major limitation is that most photoactivable compounds/systems respond only to UV irradiation, but not near-infrared (NIR) light that offers a deeper tissue penetration depth and better biocompatibility. This paper reports a simple NIR-to-UV upconversion nanoparticle (UCNP)-based siRNA nanocarrier for NIR-controlled gene silencing...
December 26, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Shao-Chi Cheng, Kai-Jen Chen, Yuji Suzaki, Yoshitaka Tsuchido, Ting-Shen Kuo, Kohtaro Osakada, Masaki Horie
This study investigated the dynamic photoresponse of pseudorotaxane crystals with azobenzene and ferrocenyl groups in the axle component. X-ray crystallography showed pseudorotaxanes with a methylazobenzene group and a dibromophenylene ring in the cyclic component to exhibit twisting of the trans-azobenzene groups at torsion angles of 17° and 38°, respectively. Repeated alternating laser irradiation of the crystals at 360 and 445 nm produced bending of 20-30° in opposite directions, with no evidence of decay...
December 23, 2017: Journal of the American Chemical Society
Fabrizio Andrea Pennacchio, Chiara Fedele, Selene De Martino, Silvia Cavalli, Raffaele Vecchione, Paolo A Netti
In materials science there is a considerable interest in the fabrication of highly engineered biomaterials that can interact with cells and control their shape. In particular, from the literature the role played by physical cell confinement in cellular structural organization and thus in the regulation of its functions has been well established. In this context, the addition of a dynamic feature to physically confining platforms aiming at reproducing in vitro the well-known dynamic interaction between cells and their microenvironment would be highly desirable...
December 20, 2017: ACS Applied Materials & Interfaces
Seung Pyo Jeong, Lawrence A Renna, Connor J Boyle, Hyunwook S Kwak, Edward Harder, Wolfgang Damm, Dhandapani Venkataraman
Energy densities of ~510 J/g (max: 698 J/g) have been achieved in azobenzene-based syndiotactic-rich poly(methacrylate) polymers. The processing solvent and polymer-solvent interactions are important to achieve morphologically optimal structures for high-energy density materials. This work shows that morphological changes of solid-state syndiotactic polymers, driven by different solvent processings play an important role in controlling the activation energy of Z-E isomerization as well as the shape of the DSC exotherm...
December 19, 2017: Scientific Reports
Yasuhiro Shiraishi, Miyu Katayama, Masaki Hashimoto, Takayuki Hirai
Visible-light irradiation (λ < 600 nm) of commercially-available CdS in alcohol successfully promotes hydrogenation of azobenzene to hydrazobenzene with more than 95% selectivity. This is promoted by strong adsorption of azobenzene to the photoformed zerovalent Cd species adjacent to the surface S vacancies on CdS; this leads to efficient reduction to hydrazobenzene.
December 18, 2017: Chemical Communications: Chem Comm
Pedram Tavadze, Guillermo Avendaño-Franco, Pngju Ren, Xiaodong Wen, Yongwang Li, James P Lewis
Azobenzene is a very important system which is often studied to better understanding light-activated mechanical transformations via photoisomerization. The central C-N=N-C dihedral angle is widely recognized as the primary reaction coordinate for changing cis- to trans-azobenzene and vice versa. We report on a global reaction coordinate (containing all internal coordinates) to thoroughly describe the reaction mechanism for azobenzene photoisomerization. Our global reaction coordinate includes all of the internal coordinates of azobenzene contributing to the photoisomerization reaction coordinate...
December 13, 2017: Journal of the American Chemical Society
Maria Montagna, Olga Guskova
In this computational work we investigate the photosensitive cationic surfactants with the trimethylammonium or polyamine hydrophilic head and the azobenzene-containing hydrophobic tail. The azobenzene-based molecules are known to undergo a reversible trans-cis-trans isomerization reaction when subjected to UV-Visible light irradiation. Combining the density functional theory and the all-atom molecular dynamics simulations, the structural, optical and the hydration properties of the trans- and the cis-isomers and their interaction with the oppositely charged poly(methacrylic acid) in aqueous solution are investigated...
December 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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